Because technology for mobile electronic devices is improving constantly, optical imaging lenses are developed diversely. As a result, applications of mobile electronic devices are not only limited to taking pictures or videos and further have telephoto photography function to satisfy consumers' demands. Consumer demand for imaging quality have increased with continued improvements to optical imaging lenses. With respect to a conventional telephoto lens, its length is generally larger than 50 mm, and its Fno is 4 or more than 4. Thus, a conventional telephoto lens generally cannot satisfy consumer demands.
To preserve good imaging quality, the materials of the optical imaging lens and manufacturing yield should be considered when reducing the size of the optical imaging lens. In this manner, there is a desirable objective for improving an optical imaging lens having six lens when maintaining a good imaging quality and yield.